Well, to put a star on a Christmas tree, you would need to first find the perfect star for your tree. Then, you would need to find a spot on the top of your tree that is wide enough to place the star. Once you've found the spot, you would need to carefully lift the star and place it on top of the tree. Be sure to balance the star so it doesn't fall off and you may need to adjust it slightly to make sure it's centered.